2024-05-13 13:54:33
The earthquakes occurred in Vogtland, a region known for regular low-level earthquakes. These tremor cycles usually last for several weeks and the tremors themselves are usually weak. The largest known earthquakes in the region were around magnitude 4.5, says Torsten Dahm, a geophysicist at the German Geosciences Research Center GFZ, who heads a monitoring project in the region.
He and his colleagues recently completed the installation of a new network of seismometers installed in boreholes in the Vogtland area. These seismometers recorded an earthquake in late March that was different from others in the area – compared to previous earthquakes, the epicenter of the latest one jumped 15 km to the north. Furthermore, the earthquake appears to have occurred not on a vertical underground fault line, but on a near-horizontal underground structure.
“It was a bit of a new observation and a surprise for us,” says T. Dahm. This shows the complex seismic situation that lies beneath this picturesque region of hills and green meadows.
Vogtland is far from the edges of tectonic plates. According to Dahm, it is not yet clear why the earthquakes occur in the area, but they are most likely caused by carbon dioxide rising from magmatic fluids about 50 km deep. There are no active volcanoes in the area and there is very little evidence of ancient volcanic activity.
One of the most important questions facing the research team is whether the melting magma itself is actually entering the crust beneath the region from the mantle, or whether the tremors are caused by fluids and gases released by the magma.
Dahm says that pressure forces in the crust would likely prevent this magma from erupting, but it could build up in the crust over time. If so, it would affect the evolution of new volcanoes over tens of thousands or hundreds of thousands of years. In other words, if the magma builds up, this currently quiet region could one day erupt in volcanoes. Alternatively, the magma may simply remain below the surface and never cause more than minor earthquakes.
The results of the study may also have implications for seismic activity in other regions where volcanic activity is possible.
“Now, with these very precise observations of seismic activity, there is a good opportunity to better answer the question, ‘What actually causes earthquakes?'” says Dahm.
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2024-05-13 13:54:33